Merge remote-tracking branch 'proofsearch-import/master'

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diff --git a/proofsearch/include/atp/search/clause_queue.h b/proofsearch/include/atp/search/clause_queue.h
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+/*
+ * richard-atp-engine: A saturation-based automated theorem prover for first-order logic.
+ * Copyright (C) 2026 Richard Qin
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+/// @file clause_queue.h
+/// @brief Priority queue for the Given Clause Loop.
+
+#include "atp/core/clause.h"
+
+#include <functional>
+
+namespace atp {
+
+/// Comparison function type for clause ordering.
+using ClauseComparator = std::function<bool(const Clause& a, const Clause& b)>;
+
+/// BFS comparator: prioritize shallower derivation depth.
+inline bool bfsCompare(const Clause& a, const Clause& b) {
+    return a.depth_ > b.depth_;  // min-heap by depth
+}
+
+/// Weight comparator: prioritize shorter (fewer literals) clauses.
+inline bool weightCompare(const Clause& a, const Clause& b) {
+    return a.literals_.size() > b.literals_.size();  // min-heap by literal count
+}
+
+}  // namespace atp